If you are using Amazon S3 for storage, I recommend using IAM to create users with specific access to S3 only or to some specific bucket only. It is great way to give to your developer or client or partner access to specific bucket in your S3 without allowing access to whole Amazon or AWS or S3 account.

Using IAM service in AWS, you can create groups and users with specific permissions. In my case:

I created a group called: test

then added: testuser as a user in the group

Used following policy for the group to give access to only ‘test’ bucket